This invention relates to a tractor trailer power system and especially to a trailer power system which is independent from the tractor and main engine for operating the trailer liftgate and other power components to prevent tractor idling.
Auxiliary power units are commonly provided for auxiliary cooling, heating and power to trucks having semi-trailers and they are especially common with cross-country truckers. Trucks used for long hauls are generally equipped with a sleeper compartment located in a truck cab to provide a convenient place for a trucker to sleep. The truck has a main engine which typically has a heating system including a heater in the cab of the truck as well as an air-conditioning system for the truck cab. However, when the trucker parks a truck to rest or sleep, the heater or air-conditioning in the sleeper requires the continuous running of the truck's engine. It is inefficient to run the truck's engine to merely provide heating and air-conditioning and is more efficient to use auxiliary power units which usually have a small auxiliary engine to provide power for heating or cooling.
Large tractor trailer trucks have large trailers connected to a fifth wheel of the truck and commonly have a liftgate which is hydraulically operated for loading and unloading the truck. Truck trailers of this type also frequently carry a pallet mover for moving heavy loaded pallets into and out of the trailer. These pallet movers are electrically powered through batteries which are typically re-charged from a 110 volt AC source.
The trailer hydraulic liftgates are driven by hydraulic fluid powered by an electric motor driven hydraulic pump which in turn is powered by liftgate batteries. The liftgate batteries are charged from the main engine of the truck. When a trailer is disconnected from the truck or tractor and left in place without the truck, there is no truck engine to power the alternator for recharging the liftgate batteries. The trailer then generally sits idle until the tractor returns so that the liftgate can be operated and the truck unloaded or loaded. This can provide for a great deal of lost time in the loading and unloading the trailer. Currently, tractors must have their engines running to charge the trailer batteries.
The present invention is directed towards an auxiliary power source which can continuous recharge the liftgate batteries so the tractor engine can be turned off. The present auxiliary power source can also provide a handy power reeled cable for attaching to the pallet lifters and movers so that the trailer can be fully operational for loading and unloading without the truck engine running.
In the past, there have been numerous auxiliary power systems for trucks including U.S. Pat. No. 5,333,678 to Mellum et al. for an auxiliary power unit for a truck having a cab and a sleeper to provide auxiliary power for auxiliary air conditioning and heating without having to keep the main truck engine running. In the Kennedy U.S. patent application Publication No. 2002/0056993 an integrated conventional air conditioning system for trucks has an auxiliary power source to drive the compressor when the main engine is not operated. In the Gear U.S. Pat. No. 4,682,649 an auxiliary air conditioning, heating and engine warming system for trucks includes a small lightweight auxiliary power plant which includes an engine, an electrical alternator, water pump, air conditioning compressor, and heat exchanger mounted on the tractor or truck for providing auxiliary power for the electrical system when the truck engine is not running. In the Willis U.S. Pat. No. 5,528,901 a compact auxiliary power system for heavy duty diesel engines and methods is provided while the Whittaker U.S. patent application Publication No. 2003/0070849 provides an auxiliary power unit for vehicles. The Wurtele U.S. Pat. No. 7,245,033 is an auxiliary heating and air conditioning unit for diesel powered transport vehicles while the Nijjar et al. U.S. Pat. No. 4,762,170 is an auxiliary power system for trucks and other heavy duty vehicles. The Eckstein et al. U.S. Pat. No. 4,448,157 is an auxiliary power unit for vehicles.
These prior art auxiliary power units are typically mounted on the truck for providing power to the truck for driving the heating and air conditioning systems without leaving the truck's main engine running. Auxiliary power units have also been utilized in emergency vehicles for providing emergency power. Typically, these vehicles obtain their power from the main engine of the vehicle. Currently, the main engine needs to be idling to keep the auxiliary batteries charged.
The present invention on the other hand is directed towards a separate auxiliary power supply for the tractor trailer to keep the trailer operational for loading and unloading when the truck is disconnected from the trailer. It also prevents idling the tractor engine which typically consumes one gallon per hour while the auxiliary power unit consumes 0.1 gallon per hour and only runs when the batteries are low and shuts off when they are charged.